Best available cop



Feb; 22 1927.

, BEST AVAlLABLE com 1,618,766 c. MACMILLAN CBNTRIFUGALLY OPERATED CONTACT IAKIRG DEVICE Filed lay 17. 1924 Inventor Campbe-LL' macmLLLan b d, is Attorney Patented Feb. 22, 1927.

UNITED STATES 1,618,766 BEST AVAILABLE COP.

PATENT OFFICE.

CAMPBELL MACMILLAN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGALLY-OPERATED CONTACT-MAKING DEVICE.

Application filed May 17, 1924. Serial No. 714,181.

My invention relates to centrifugally operated contact making devices, and while applicable to such devices generally, it is particularly adapted to contact making devices such as are used in starting alternating current electric motors in which the secondary member is provided with a closed circuited winding having a resistance in circuit with said winding for the purpose of prodii cing a good starting torque, the said resistance being gradually cut out of circuit step by step as the speed of the motor increases.

Centrifugally operated starting devices have long been used in starting alternating current motors of the wound rotor type. These sta-rting devices are connected in the secondary circuit of the motor and operate to short-circuit the different units of resistance as the speed of the motor increases. In order to control such a motor in the above manner, it is desirable to provide more than one step of resistance together with the necessary switches so that the variations of current and torque of the secondary circuit can be varied gradually. These devices as heretofore constructed require considerable space and are expensive to build.

My invention consists in a novel construction of a centrifugally operated device which requires but a single resilient means for biasing a plurality of switches against centrifugal force. and which secures a marked economy of space and cost as compared with such devices as heretofore constructed.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of my invention and the advantages thereof, reference may be had to the following description taken in connection with the accompanying drawing, in which Fig. 1 is a side elevation showing a centrifugally operated contact making device embodying my invention; Fig. 2 is a fragmentary end elevation of the embodiment shown in Fig. 1, and Fig. 8 is a diagrammatic view showing the manner of connecting .a switch embodying my invention to a three phase rotor winding of an induction motor. 1

In Figs. 1 and 2 of the drawing, a contact makmg device embodying my invention is shown mounted upon a rotatable shaft 10 and is provided with two contact carrying arms 11 and 12 which are adapted to move outwardly in response to different speeds of rotation and establish difi'erent electrical connections as the speed of the shaft 10 increases, These arms 11 and 12 are biased against movement due to centrifugal force by a single resilient means 13 which by reason of its location exerts a different biasing effect upon the arms 11 and 12 and thus permits them to respond to centrifugal force at different speeds of rotation, and in the present embodiment they short-circuit different sections of resistance to thereby vary the resistance of the secondary circuit of the motor and thus produce the desired characteristics for the successful starting of the motor.

The arms 11 and 12 are mounted upon. pivots 1 1 and 15 respectively. which are carried by a member 16 mounted upon the shaft 10. These arms extend in the same direc tion from their pivots. The member 16 is provided with'a cover or enclosing member 17. This cover 17 supports contacts 18 and 19 which are arranged adjacent one another and are connected to a resistance unit 20, also carried by the cover 17. The arms 11 and 12 carry contacts 21 and 22 whichcooperate respectively with the contacts 18 and 19 to successively short-circuit different sections of the resistance unit as the speed of the motor increases. The pivots 14 and 15 of arms 11 and 12 are located at different distances from the center of rotation on the. shaft 10 and the resilient means 13 is located between these pivots, and is secured at one end to one of said arms and at its other end to the other of said arms in such a manner that it lies between the arms and extends substantially parallel thereto. In the drawing, the outer arm 11 is shown having a projection 23 at its free or contact end which extends toward the inner arm 12 and engages the latter when the device is at rest,

whereby said inner arm acts as a stop for said outer arm. The arm 12 is shown as haring a projection 24 located on the opposite side or back of the pivots 14: and 15, some- 6 wha emoge fLOII Il'llOJJlYO t 15, nndextending owhrd'the Jeri-m l 1.t 23 and 24 are provided with counter sunk holes throu h which screws 25 'ezt'fienrl. lfiese s'crew'se'hfizige tfi'reirdd plugs 26 which 10 are inserted in ne'er-ra arena resilient i'ri'ez'ms 13, which in the present embodii nent isshown as a. helical tension spring. By 't-u'rhing' either of the screws 2 the tension of the spring 13 can be varied 'as"cleired. Tl'leee' f W 25 age; .pi oyiglegl. w th eon cal heads which rest in the counter sun m'pieqt pe ndfl liit qrmem in e 19%? i L pernnt. the spring oree with respect spran a, themin'their-lnitial iosition Theprimary a: fteking littleipore spzrc than pstlrey are about .to eh'gm Q;wh1eh,-wonld. be secured by a true sq et QPPQ t :1: ribed errengement, the

ball and .oseip e e men .spnce, .reqg re o a clditioilel space for. rein- .ir rn veiee th com ned; space joccnp e .by the movable difiersfrorn tlra t occupied by hea s see z y 9 fobjee t. ,l this fort pi: construction is to er e.e y= 9 'si e e'by ies t e s ew e .le l e elw h We. comp etegmoyements are li'ected by parts th t. equ r for a :,.single. de\ u ;e. If it is: desired to, change the #1150 'ogthe speeds of the two let'ers 11 5nd 1 it is' possible to do so wi thputdestro ing the symmetry of position zind' balance of the unit as a whole.

ll. 9" 'l his f alrrfgingement also permits the spring 1 3 ,to adjust if. so. z 1s to a'pplyforce in q sgaig ht line between the arme ll and 12, so m t tl ie .mornerit z rr'n ofji'esisting force y f! l l zrnd 12 1s reduced as the 21 1:5118 I1' l0\ 3 011i.-

un dly 'l h ls reduction of the resisting n on errtroperzrtes to, reduce the stnlnht of th m-me lene quick or snzip mo\' ement of the arms 11 and the spring 13.01 each of the arms contac ts IS aml 19 inakc ungl bregl: in the circuits controlled i thereby fllie rust-ability snap not-ion thus imparted tot-l re nuns 11 and 12 by the spring I .13 is d'etei niinedby the loezrtion of the projeetionQt with'respect to' 't h e pivo ts 14 amt 15, for instance, the (list' ce betwomr ".ction 2-t i1nrl pi\"ot 15 increased I V a ri e e h l cat on of the projection 2t. .inoinerit arin ofireslistingforce exerted by holes of the Vi ing that the arm will not start to more ontwz-zrdy until after arm 1.1. has reached its extreme outer or emit-act umking position and that when the arm 12 begins to mm putwzn lly rlneto inrrenserl pcntrifugal the hi 'inenUm ni of opposing force exerted by spring 13 will decrease and eventually permitthis snap action to occur in "arm 12.

Withthesprin'g 13 supported and biasing the a rn1s 1 1 ancl 12 againstnioven'ient, as 'ehownfforeee 'z'ipi'ai'fi firinfe to those required g-gtfiu'o speerls in thc :ipproxinmte ratio of two toon' urebhtuinecl. This result cle- ])1 l(l$ t[)()fl liifl lflojitfi selection ofihree factors :which' are, the'eifetive weights of' the {ii-"mg which *gii'b iYhieiis nre" of the nu ash mating- 1uriru iirfmi :the {e "dietzinfces (if these 'ihiis the axis of the 'nnih Elia-ft, whicli il'tei 'tlie i 'rn i s eifei' i ri'fi1g i1*foi'ce zind, h treath e tse izrbr spring 13 'zibont pivots l ifgin'd 15 to the lei ers 11 l2 as liereinbe fore'described. 'After rhirl tit"si ds r hienjtne we fle'rers ff gi' egi 1 en J, o e at h v een 1 determined by snitgrble 'ralnes o f't-h e' three fzi ctors 'ihentitihedzig propriate absolute 'nlues may bef'given to tli ese speeds byf i'ar ing the t en's ioncf the spring 13 by 'ihez'ins' oTsci-ews'25.

lingrticnll ijiir Fig 3 o'f' ithe clrmving"\i"here in i ri'entio'ii is sh-met 'co'nnectil to :fi'otor wintlingf ill i of :i1 f tiiree "ph'nsc iiuhictien niot-or of th "woundrotor' type' in"\\'lii :h a pair of cont-net czirryir ii'rn'is ll Enid 12 end n'resistiineiinit are provided" in ent-h phase of the rotor bff'uie inotor.

\l'lrch zi phir:ilit- (hf-n zs 1'1 51m] 12 are lnsed with :i l l'ui-n!itj.-" oi 'r'ei. stances 20 us "n'l oii uclzip'teo to 21. iiiiilti ilizisrs iniluc'tion "mom-r, 'thetontei "urine 11 nre Eulju'stcrl to 'rn'ove 'or'i'tirarkli i siinnltziiihoiisl: "t :iertain prc det i iiccl ;Sw1f 1gd*uu;ems 12 are also adjusted to niorc ont'n'urtitv sininl't:ineousl ut. :i higher picilrt-ei'iiiinl spocal to t-l is' insure n iiilni iveii elm-(r3: giuuli'tion in uugnurm-m phnseisol'the rotonw-iriruii. Yi'hnt I claim us neii" and desire to r 'izjulu b Letters T itent or the United States, is: 4 l. in a cvn'triingzziltr operated contact ni 'iliing' device. 'thc omlii (ion of u plurality of iiitlc veiitienti rim-51w carrying :irn'is iidn'pte. to more rte-arr. 5 rotation pivots 'for' s'aid'j'zi'rnis', said "zirins'esiending in thejsiun'ef c'lir'ot'io'n fronr'the pivots, a plurality of stationary oiita't' "1 z 1"n gee afient. onEi'nOtheifand single resilient inzms 'for'"bili'sing said hontaet carrying arms against movement due to centrifugal force, said arms cooperating respectively with said contact members to suecessively make contact therewith as the speed of rotation of the device increases.

2. In a centrifugally operated contact making device, the combination of a plurality of independently movable contact carrying arms arranged in and adapted to move outwardly in the same plane in response to different speeds of rotation. and a single resilient means extending parallel with and between said contact carrying arms for biasing them against the movement due to centrifugal force.

3. In a centrifu'gally operated contact making device, the combination of a plurality of independently movable contact carrying arms adapted to move outwardly in response to different speeds of rotation, a projection on each of said contact carrying arms extending toward the other of said arms, and a single resilient means supported upon and between said projections for biasing said contact carrying arms against movement, said resilient means extending parallel with and between said contact carrying arms and exerting a difi'erent bias ing effect upon each of said arms.

4. In a centrifugally operated contact making device, the combination of a plurality of independently movable contact carrying arms adapted to move outwardly in response to different speeds of rotation, a projection on each of said contact carrying arms extending toward the other of said arms, and a resilient means supported at one end to one of said projections and at its other end to the other of said projections, said resilient means extending parallel with and between said contact carrying arms and biasing said contact carrying arms against movements due to centrifugal force.

5. In a centrifugally operated contact making device, the combination of a plurality of independently pivoted contact carrying arms adapted to move outwardly in response to difierent speeds of rotation, pivots for supporting said arms, a projection on each of said contact carrying arms extending toward the other of said arms, and a resilient means supported at one end to one of said projections and at its other end to the other of said projections. said resilient means extending parallel with and between said contact carrying arms and biasing said contact carrying arms against movements due to centrifugal force, said projections and said resilient means being so located with respect to.said pivots that the moment arm of resisting force exerted upon the contact carrying arms is reduced as the speed of the motor increases.

6. In a centrifugally operated contact making device, the combination'of a plural- BEST AVAILABLE COP.

ity of independently movable contact carrying arms adapted to move outwardly in response to diiierent speeds of rotation, a projection on each of said contact carrying arms extending toward the other said arms, the projection on the outer of said arms engaging the-inner of said arms when said device is at rest whereby said inner arm acts as a stop for the outer arm, and a single resilient means supported upon and between said projections for biasing said contact carrying arms against movement, said resilient means extending parallel with and between said contact carrying arms and ex erting a different biasing effect upon each of said arms.

7. In a centrifugally operated contact making device, the combination of a plurality of independently movable contact carrying arms adapted to move outwardly in response to different speeds of rotation, a projection on each of said contact carrying arms extending toward the other said arms, pivots for said arms, said arms extending in the same direction from their pivots, and a single resilient means supported upon and between said projections for biasing said contact carrying arms against said movement, said resilient means extending parallel with and between said contact carrying arms and exerting a different biasing efiect upon each of said arms.

8. In a centrifugally operated contact making device, the combination of a plural ity of independently movable contact carrying arms adapted to move outwardly in response to different speeds of rotation, a projection on each of said contact carrying arms extending toward the other of said arms, pivots for said arms, said arms extending in the same direction from their pivots, a plurality of stationary contact members arranged adjacent one another and a single resilient means supported upon and between said projections for biasing said contact carrying arms against said movement, said resilient means extending parallel with and between said contact carrying arms, said arms cooperating respectively with said contact members to successively make con tact therewith as the speed of the rotation of the device increases.

9. In a centritugally operated contact making device, the combination of a plurality of independently movable contact carrying arms adapted to move' outwardly in response to different speeds of rotation, a projection on each of said contact carrying arms extending toward the other of said arms, the projection on the outer of said arms engaging the inner of said arms when said device is at rest whereby said inner arm acts as a stop for the outer arm, pivots for said arms, said arms extending in the same direction from their pivots, a plurality of loo stationaryc0ntac-t."ii1e'nibers arranged adjetions for biasing said contact carrying arms against movement, said *resilient m'eans' extending parallel witlranci between said contact carrying armsand-eXerting a different biasing 'eflect'=upon"'each of said" arms; said BEST AVAILABLE COP.

arms cooperating respectively with saidcontact members to successively m'a-ke contact. 10 therewith as the speed 0f'-r0t:1tinn of the device increases.

In witness whereof, I have 'herennt-oset my hand this 16th day of May, 1924,

CAMPBELL M ACMILLAN. 

